Processing Induced Warpage in Composite Cylindrical Shells

This paper investigates a cause for warpage in structures manufactured using filament winding or fiber placement. This warpage phenomena has been determined to be caused by fiber/resin consolidation resulting from manufacturing parameters including: cure pressure, winding tension, and material system characteristics. This is a non-thermal phenomena and is independent of cure temperature, or finished part operational environments. A novel theory has been developed to predict the warpage or “springback” resulting from the processing induced strain gradient that develops in laminates due to the consolidation. This paper utilizes a strain model derived previously to develop a warpage prediction model utilizing Classical Laminated Plate Theory (CLT). This theoretical solution is than compared to experimental results for hoop wound test specimens. The end goal of the research is to develop a springback prediction model that can be applied to large scale parts utilizing consolidation parameters measured at the coupon level.